The present invention relates to an energy collecting system and a method of operating the same in which energy is collected through generation of electric power by a waterwheel using water used by, for example, an air-conditioning load or the like in a building.
For example, as an air-conditioning system in a building, there has been widely employed an air-conditioning system of heat storage type in which a heat source is operated using inexpensive nighttime electric power to store generated heat in a heat storage. In the daytime in which air-conditioning load takes place, the stored heat is fed from the heat storage to the load, i.e., an air conditioner to achieve air-conditioning operation.
FIG. 12 is a diagram showing a configuration of an example of the prior art, namely, an open-loop air-conditioning system of heat storage type. In a primary-side system S1, the configuration includes a water pump 1 which feeds water from a heat storage 16 to supply the water via a water supply pipe 4a to a heat source 4 and a both-end motor 2 of which one shaft end is directly coupled with the water pump using a shaft coupling to drive the water pump. The other shaft end is coupled with a waterwheel 12 via a clutch 12b. The waterwheel is disposed at a position at which potential energy of water discharged from the heat source can be completely collected. Numerals 18 and 19 indicate electric power sources, numeral 5 is a two-way valve to adjust a quantity of heat generated by the heat source, numeral 6a is a water supply pipe connecting the heat source to the waterwheel, and numeral 6 is an expansion tank associated with the water supply pipe. The tank 6 breaks a siphon to apply a head of the supplied water (potential energy thereof) to the waterwheel. In place of the expansion tank, a vacuum breaking valve may be disposed depending on cases. Numeral 12c indicates a water supply pipe to return the water from the waterwheel to the heat storage. That is, the water supplied to the heat source 4 by the water pump 1 is heated by the heat source and is then fed to the waterwheel 12. The waterwheel 12 is operated by the potential energy of the water to generate power and then imparts the power to the both-end motor 2. The load of the motor becomes lower than that of the water pump, the discrepancy therebetween corresponds to the power imparted from the waterwheel. The water from the waterwheel then returns to the heat storage.
The secondary-side system S2 is a load of an air conditioner or the like and supplies water from the heat storage 16 via a water supply pipe 7a to an air han (air handling unit) 8 and a fan coil 9 by a pump 7. The air han 8 includes an adjusting valve 8a to adjust a quantity of heat. The fan coil 9 also includes a similar adjusting valve 9a. The water of which heat is radiated is returned via the water supply pipe 7b to the heat storage 16.
FIG. 13 shows an operating characteristic graph of a pump and a waterwheel in an example of the prior art. A total water pumping-up process of the pump, an effective head of the waterwheel, and power of the pump and the waterwheel are indicated along an ordinate. A water flow rate is indicated along an abscissa. A curve A is a curve of Q,H performance of the pump and a curve C is a curve of shaft power when the waterwheel is not operated. The total water pumping-up process is required to operate only the water pump to supply water at a flow rate of Q0 to the water supply system shown in FIG. 9. The operation point in this operation is point O4 on the curve A. Power consumed in this operation is L1 indicated by pump shaft power, and the operation point is point O1 on the curve C. A curve B indicates an effective head of the waterwheel (pressure head difference between the inlet and the outlet of the waterwheel). This means that when water flows at a flow rate of Q0, a pressure head difference (effective head) of H1 occurs between the inlet and the outlet of the waterwheel, and this potential energy is absorbed to generate power as below.
A curve D is a power curve when the water pump and the waterwheel are operated. Power consumed in the operation is L2 indicated by pump shaft power and the operation point is point O2 on the curve D. That is, when the flow rate is Q0, power generated by the waterwheel is L3.
In this case, the power collection ratio (L3/L1) is about 20% to about 30%.
In this way, the conventional apparatus effectively uses potential energy of the pumped-up water passed through the heat source.
For example, JP-A-50-128801 (a power collection pumping machine) and JP-A-50-49701 (a power collection pumping machine) describes known examples of this apparatus. However, the prior art technique uses a clutch to directly couple a motor with a waterwheel and there is a problem of improvement of transfer efficiency of the clutch. There exists another problem. That is, the energy collected by the waterwheel is power and there is a problem that the power cannot be used in this case, in consideration of structure, for any other load in the building. JP-A-5-10245 (an electric power generator using waterwheel of paddle-wheel type) is a known example of waterwheel electric power generation using a waterwheel in a dam, a paddy field, or a watercourse.